A Field Effect Transistor (FET) is a device in which an output current is controlled by manipulating a voltage applied to a gate electrode. Transistors, including FETs, form the building blocks of many active electronic circuits. The performance of a FET is affected by the interplay of a number of device parameters, including capacitance and resistance values between various device components. FETs are optimized through a complex tradeoff of these parameters. The optimization process must also take into account the impact of hot carrier injection (HCI). Existing designs are not flexible enough to separately optimize the gate-to-drain capacitance (Cgd) reduction and the field plate impacting the drift region of the transistor.
The complexity of FET optimization may be illustrated by noting that the inclusion of a field plate designed to simultaneously reduce the Cgd and lower the peak electric field will significantly increase the gate-to-source capacitance (Cgs). Faraday shields have been used to reduce Cgd, but such shields do not necessarily have an impact on the horizontal and vertical electric field components. Accordingly, a need exists for a device structure capable of improving device characteristics and increasing design flexibility to optimize some parameters while minimizing negative impact on others.
For simplicity and clarity of illustration, the drawing figures illustrate the general manner of construction, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the invention. Additionally, elements in the drawing figures are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of embodiments of the present invention. The same reference numerals in different figures denote the same elements.
The terms first, second, third, fourth, and the like in the description and in the claims, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein.
The terms left, right, front, back, top, bottom, over, under, and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein. The term coupled, as used herein, is defined as directly or indirectly connected in a mechanical or non-mechanical manner.